OP position means your baby is head-down but facing your belly instead of your spine. The full term is “occiput posterior,” and it’s often called “sunny side up” because the baby’s face points upward during delivery. It’s one of the most common non-ideal fetal positions, affecting roughly 15 to 30 percent of babies at the start of labor, though most rotate on their own before birth.
How OP Differs From the Ideal Position
In the ideal birth position, called occiput anterior (OA), your baby faces your back with its chin tucked to its chest. This lets the smallest part of the baby’s head lead the way through the pelvis. In OP position, the baby faces your stomach instead. This means the wider, bony back of the skull presses directly against your spine and tailbone during labor, and the baby’s head doesn’t tuck as efficiently. The result is a tighter fit through the birth canal.
You might see OP described more specifically as LOP (left occiput posterior) or ROP (right occiput posterior), depending on which side of your pelvis the back of the baby’s head is angled toward. Both are considered sunny side up.
Signs Your Baby May Be OP
Before labor, there are a few clues. If your belly feels unusually squishy rather than firm and smooth across the front, that can indicate your baby’s spine is against your spine, leaving arms and legs facing forward. You may feel kicks right in the center of your belly or notice small indentations near your belly button, which are limbs pressing outward. With an anterior baby, kicks tend to land more to the sides.
Your provider can confirm the position through an ultrasound or sometimes a physical exam during labor. Many people don’t find out their baby is OP until labor is already underway.
Why OP Position Causes Back Labor
Back labor is the hallmark of an OP delivery. It happens because the hard back of the baby’s skull grinds against your lower spine and tailbone with each contraction. Instead of feeling contractions mostly in the front of your abdomen with breaks in between, you feel deep, continuous pain in your lower back that doesn’t fully let up between contractions. Not everyone with an OP baby experiences severe back labor, but the association is strong enough that intense back pain during labor is often the first sign something is posterior.
How OP Affects Labor Length and Delivery
Labor with a persistent OP baby tends to run longer. For first-time mothers, the first stage of labor averages about 1.7 hours longer compared to babies in the anterior position (roughly 12.5 hours versus 10.8). The pushing stage runs about 13 minutes longer. For mothers who’ve given birth before, the differences are smaller: about an extra hour in the first stage and an extra 5 minutes of pushing.
The bigger concern is how delivery ends up happening. When the baby stays OP and doesn’t rotate, the rates of cesarean section and assisted delivery (using vacuum or forceps) climb significantly. In one randomized trial, persistent OP was present in the vast majority of cesarean deliveries, while only about 3 to 6 percent of spontaneous vaginal births involved a baby still in the OP position at the moment of delivery. The risk of serious perineal tearing also increases. In forceps-assisted deliveries, OP position makes significant tearing roughly three times more likely compared to an anterior position.
Most OP Babies Rotate on Their Own
Here’s the reassuring part: being OP at the start of labor does not mean staying OP at delivery. About 50 percent of babies are posterior when active labor begins, but three-quarters of those rotate to anterior (or at least to a sideways position) during the natural course of labor. Only 5 to 8 percent of all babies are actually born face-up. That number rises to around 13 percent for people who have an epidural, likely because the pelvic floor muscles that help guide the baby’s rotation are less active under anesthesia.
Techniques to Encourage Rotation
Several strategies can help nudge a posterior baby to turn, either during pregnancy or in labor. None are guaranteed, but they’re low-risk and widely used.
- Hands-and-knees positioning: Getting on all fours uses gravity to shift the baby’s weight away from your spine and toward your belly, creating space for the baby to rotate. Spending time in this position during late pregnancy and early labor is one of the most commonly recommended approaches.
- Knee-chest position: Similar to hands and knees but with your chest dropped lower toward the floor. Research has shown that both semi-prone and knee-chest positions during labor reduce the percentage of babies still in OP at birth compared to lying on your back.
- Asymmetric movements: Walking up stairs sideways, lunging, or sitting on a birth ball with exaggerated hip circles can open the pelvis unevenly, giving the baby room to shift. Programs like the Miles Circuit combine specific positions held for set intervals to encourage rotation through a sequence of postures.
- Avoiding reclining: Leaning back on a couch or lying flat encourages the heaviest part of the baby (the spine and back of the head) to settle toward your back. Sitting upright or leaning slightly forward can help.
In one study comparing positioning strategies, only about 15 percent of women using the semi-prone position and 14 percent using the knee-chest position still had a posterior baby at birth, compared to nearly 34 percent of women in the control group who labored without specific positioning guidance.
What Happens if the Baby Stays OP
If the baby hasn’t rotated by the second stage of labor (the pushing phase), your provider may attempt a manual rotation. This involves reaching in and gently turning the baby’s head to face the correct direction. Success rates vary by practitioner, ranging from about 68 to 90 percent. When manual rotation works, it often allows labor to proceed to a vaginal delivery.
If rotation isn’t successful and the baby remains OP, delivery can still happen vaginally, but it’s more difficult and more likely to require assistance with vacuum or forceps, or to end in a cesarean section. Your care team will weigh factors like how far the baby has descended, how long you’ve been pushing, and how you and the baby are tolerating labor.
Managing Back Pain From OP Labor
If you’re in labor with a posterior baby, the back pain can be intense. Beyond epidural anesthesia, there are targeted options. Counterpressure, where a partner or doula presses firmly on your lower back or hips during contractions, provides immediate physical relief by opposing the pressure of the baby’s skull. Warm compresses and getting into water (a shower or birth pool) also help.
A more specific option is sterile water injections, where small amounts of sterile water are injected just under the skin of the lower back in the diamond-shaped area above your tailbone. It stings sharply for about 30 seconds during the injection, but pain relief typically starts within 10 minutes and can last up to 3 hours. A review by the UK’s National Institute for Health and Care Excellence found these injections provided meaningful relief for back pain during labor compared to standard care, massage, or saline injections. They’re specifically recommended for back labor rather than general labor pain.
Changing positions frequently during labor also helps manage pain while giving the baby opportunities to rotate. Staying mobile, rocking on a birth ball, or alternating between hands-and-knees and side-lying positions can make a noticeable difference in both comfort and the baby’s progress.